Malathion is an organophosphate insecticide which acts as an acetylcholinesterase inhibitor. In the USSR, it was known as carbophos, in New Zealand and Australia as maldison and in South Africa as mercaptothion. Chemically it is commonly supplied as technical-grade O,O-dimethyl S-(1,2-dicarbethoxyethyl) phosphorodithioate (CAS 121-75-5), molecular formula C10H19O6PS2 and molar mass about 330 g mol-1. It is a pale yellow to amber oily liquid with low water solubility and good formulation flexibility for emulsifiable concentrates, ULV sprays and wettable powders. Malathion is relatively selective for insects because it is rapidly detoxified in many mammals by carboxylesterases, but it can be bioactivated in insects and some non-target species to malaoxon by cytochrome P450 oxidation of the P S bond to P O, producing a more potent acetylcholinesterase inhibitor. Typical uses include agricultural foliar and soil applications, stored product treatments, public health vector control and some structural pest control; label directions, concentration and allowed use sites are determined by regulatory registration in each market.
Parent: Malathion
Parent: Malathion
Parent: Malathion
Parent: Malathion
Technical malathion batches typically meet manufacturer and regulatory specifications that require high assay of active ingredient and tight control of byproducts; common commercial specifications cite active ingredient content around 94 to 98 percent by weight for technical malathion, with the balance consisting of solvent residues, synthesis byproducts and trace decomposition products. Key related compounds and impurities to monitor include isomalathion, which can form under high-temperature or poor-processing conditions and is more cholinesterase-inhibitory than parent malathion; malaoxon, the P O oxidation product and more toxic metabolite, which is normally controlled to trace levels in fresh material; and small amounts of alkyl phosphorothioates, monoesters and hydrolysis products. Typical specification limits in industry practice range by supplier and regulation: isomalathion is often limited to below about 0.5 to 1.0 percent, malaoxon to low ppm up to low tenths of a percent depending on storage and production controls, and other related impurities at trace to low percent levels; analytical monitoring is commonly done by GC with selective MS or FPD detectors and by LC methods where applicable.
Malathion is used as an agricultural and public health insecticide for control of a wide range of insects including mosquitoes, fruit flies, aphids and other foliar pests; it is formulated for aerial and ground spray, ultra-low-volume applications for vector control, and for some stored-product or structural pest treatments subject to label approval.
Malathion inhibits acetylcholinesterase and acute high-level exposures can cause cholinergic symptoms such as headache, nausea, sweating, salivation, miosis and in severe cases respiratory distress; however, malathion itself is less acutely toxic to humans than several other organophosphates because mammals detoxify it relatively rapidly and because many toxic effects require conversion to malaoxon. Chronic low-level exposure concerns focus on neurological and developmental endpoints and safe handling, personal protective equipment and adherence to label rates minimize risk.
Malathion is not universally banned in India; it has been used in agriculture and public health programs, but its permitted uses, formulations and application methods are subject to national and state regulatory controls and periodic reassessments. Specific local restrictions or cancellations of particular product labels can occur, so users should consult current Indian regulatory lists and product labels for allowed uses.
Malathion has not been broadly banned across the United States at the federal level; instead the US EPA has re-evaluated organophosphate registrations over time and has restricted or cancelled certain residential or indoor uses of some organophosphates based on risk assessments and available safer alternatives. Some specific formulations or uses of malathion have been modified or phased out under regulatory review to reduce human exposure, while other uses remain registered with label restrictions and mitigation measures.
